The small, free-living nematode Caenorhabditis elegans is gaining favor as an organism in which to study the genetic basis of animal development, behavior and aging. This is primarily because of its relatively simple anatomy (about 810 nongonadal nuclei), short life cycle (3 days), defined life span and suitability for genetic analysis. Developmental studies include the following: analysis of embryonic cell determination using cell culture, mutants, and laser microbeam ablation; studies of the role of cell interactions and cell lineages in specifying post embryonic cell differentiation; examination of cellular morphogenesis in muscles, neurons, cuticle and gametes; analysis of biochemical and morphological changes accompanying senescence in wild-type, life span mutants, and in mutants which accumulate in a non-aging, Dauer larval state. Many individual genes have been isolated by using recombinant DNA techniques and these are being used to probe the mechanism of genetic regulation during development of mutants and wild-type. A complete wiring diagram of the nervous system has been prepared from serial electron micrographs and analysis of neuronal function is proceeding with behavioral mutants, laser microbeam ablation and electrophysiological studies on the larger nematode Ascaris which has a nearly identical wiring diagram. Mutants altering specific enzymes in neurotransmitter biochemistry are being studied both developmentally and functionally. The objective of the C. elegans Meeting is to bring together people working on these and other diverse aspects of C. elegans biology so that they may enlighten, criticize and stimulate each other and hence advance the field. This grant application is for a meeting in 1981 and one in 1983, since it has been agreed to meet biennially.